我遇到一个父进程可能产生多个子进程的情况。 我想要实现的是，如果父进程被终止或退出，那么它的所有子进程都应该与父进程一起终止。

在帖子(下面的链接)中，我发现了通过让父进程成为组长来存档它的建议。 如果我没理解错的话，这也是流程组的主要目的。我说得对吗？
帖子还提到 prctl(PR_SET_PDEATHSIG, SIGHUP);和其他一些方法，但它们是以太操作系统特定的，否则就不会那么优雅。

我已经编写了一个小演示来尝试更好地理解事情，但它并没有按我预期的方式工作。我做错了什么？

//https://www.andrew.cmu.edu/course/15-310/applications/homework/homework4/terminalgroups1.html
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <stddef.h>
#include <errno.h>
#include <string.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/termios.h>

int main()
{
    int status;
    int cpid;
    int ppid;

    ppid = getpid();
    printf("parent: %d\n", ppid);

    if (!(cpid=fork()))
    {
        printf("child: %d\n", getpid());
        if(setpgid(0,ppid) == -1)
           printf("child setpgid errno %s\n", strerror(errno));
        else
           printf("child gid %d\n", getpgid(0));
        pause();
        printf("child exited\n");
        exit (-1);
     }

     if (cpid < 0)
         exit(-1);

     setpgid(0, ppid);
     if(setpgid(0,0) == -1)
         printf("parent setpgid erno %s\n", strerror(errno));
     else
         printf("parrent gid %d\n", getpgid(0));


     sleep(7);
     printf("parent exit\n");
     exit(0);
}

这篇文章涉及在以下方面提出的建议: * How to make child process die after parent exits?

最佳答案

请注意，只有在非常有限的情况下才会向子进程发送信号。 POSIX说:

• If the process is a controlling process, the SIGHUP signal shall be sent to each process in the foreground process group of the controlling terminal belonging to the calling process.

• If the process is a controlling process, the controlling terminal associated with the session shall be disassociated from the session, allowing it to be acquired by a new controlling process.

• If the exit of the process causes a process group to become orphaned, and if any member of the newly-orphaned process group is stopped, then a SIGHUP signal followed by a SIGCONT signal shall be sent to each process in the newly-orphaned process group.

controlling process的定义是:

The session leader that established the connection to the controlling terminal. If the terminal subsequently ceases to be a controlling terminal for this session, the session leader ceases to be the controlling process.

通常，您的进程不会成为与控制终端(通常是您的 shell)建立连接的 session 负责人。

如果有 POSIX 的其他部分适用，请通知我。

我对您的代码 (termkids.c) 进行了一些测试:

#include "posixver.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>

static void sigcatcher(int signum)
{

  printf("%d: Signal caught: %d\n", (int)getpid(), signum);
  exit(1);
}

int main(void)
{
    int cpid;
    int ppid;

    ppid = getpid();
    printf("Parent  PID:  %d\n", ppid);
    printf("Initial PGID: %d\n", (int)getpgid(0));
    if (setpgid(0, 0) != 0)
    {
      fprintf(stderr, "setpgid() failed (%d: %s)\n", errno, strerror(errno));
      return 1;
    }
    printf("Revised PGID: %d\n", (int)getpgid(0));

    if ((cpid=fork()) < 0)
    {
      fprintf(stderr, "fork() failed (%d: %s)\n", errno, strerror(errno));
      return 1;
    }
    else if (cpid == 0)
    {
        cpid = getpid();
        printf("Child PID:  %d\n", cpid);
        printf("Child PGID: %d\n", (int)getpgid(0));
        (void)signal(SIGTERM, sigcatcher);
        (void)signal(SIGHUP,  sigcatcher);

        pause();
        printf("%d: child exited\n", cpid);
        return(-1);
     }

     printf("Parent - sleeping\n");
     sleep(7);
     printf("Parent exits\n");
     return(0);
}

示例输出:

$ ./termkids
Parent  PID:  17701
Initial PGID: 17701
Revised PGID: 17701
Parent - sleeping
Child PID:  17702
Child PGID: 17701
Parent exits
$ ps
  PID TTY          TIME CMD
  388 pts/5    00:00:00 bash
17702 pts/5    00:00:00 termkids
17707 pts/5    00:00:00 ps
$ kill 17702
17702: Signal caught: 15
$

请注意，kill 17702 是在父进程完成几分钟后发送的。

关于c - 进程组中的进程是否应该在 Unix/Linux 中与其父进程一起终止？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23624640/